The SIARI Score: A Novel Decision Support Tool Outperforms LRINEC Score in Necrotizing Fasciitis

Background The Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) scoring system was developed to aid the diagnosis of necrotizing fasciitis and guide management [1]. Aim To validate the LRINEC score and identify clinical predictors to develop a refined diagnostic scoring tool for the diagnosis of necrotizing fasciitis at Middlemore Hospital, New Zealand. Methods This was a retrospective case-control study of patients admitted to Middlemore Hospital with necrotizing fasciitis and severe cellulitis between January 2000 and December 2010. The LRINEC scores at admission were evaluated for performance in discriminating between cases of necrotizing fasciitis and severe cellulitis. Cases and controls were randomized into developmental and validation cohorts. Univariate and multivariate logistic regression analysis of demographic, clinical, and laboratory variables for the diagnosis of necrotizing fasciitis was performed. The identified independent predictors were used to develop a new diagnostic scoring tool. Results The area under the receiver operating characteristic curve (C-statistic) of a LRINEC score >= 6 for the diagnosis of necrotizing fasciitis was 0.679. The newly developed SIARI score [Site other than the lower limb, Immunosuppression, Age < 60 years, Renal impairment (creatinine > 141), and Inflammatory markers (CRP >= 150, WCC > 25] demonstrated superior diagnostic ability compared with the LRINEC score in both the developmental (C-statistic: 0.832 vs. 0.691, p < 0.001) and validation cohorts (C-statistic: 0.847 vs. 0.667, p < 0.001). Conclusion The LRINEC score exhibited only modest discriminative performance in this cohort, while the SIARI score is a simplified tool that demonstrates superior diagnostic ability for detecting necrotizing fasciitis. Future external validation studies are required to confirm the trends observed in this study.